Support decompiling binaries

[simonlindholm]

A bit tricky, since we'd have no %lo/%hi markers or function names... But maybe we could have a mode for "decompile the byte range A..B, and auto-generate global variable names"?

Alternatively, we should add documentation on how to use n64split to get a .s file in the right format for mips_to_c to use.

[matt-kempster]

copy-pasting my thoughts from discord:

in my opinion we should not extend the decompiler to also be a disassembler
unix philosophy: do one thing, do it well
I wholeheartedly agree that we should hook into n64split, including its documentation
but I don't think we need to reimplement it